Increasing Wear Resistance of Copper Electrode in Electrical Discharge Machining by Using Ultra-Fine-Grained Structure

Abstract

Tool electrode wear is a severe problem in electrical discharge machining (EDM) which significantly affects the efficiency of the machining process and dimensional accuracy. In this paper, ultra-fine-grained (UFG) structures due to their unique and unusual properties are used to alleviate the wear problem of tool electrode. Equal-channel angular pressing (ECAP) is a novel severe plastic deformation metal forming process which can produce ultra-fine to nanoscale grains in bulk materials. Commercially pure copper was ECAP-ed to produce UFG microstructures and then used as tool electrode in EDM. The performance parameters in the EDM process, which have been studied, are material removal rate (MRR), volumetric electrode wear (VEW) and electrode wear ratio (EWR). For UFG and coarse-grained electrodes, the MRR, VEW and EWR obtained in EDM process have been compared. The results show that VEW and EWR decrease when UFG copper tool electrodes are used. But with increasing machining time, VEW and EWR of UFG copper electrodes approach those of the coarse-grained copper electrode.